A desert tortoise walks around behind the Shoshone Inn next to Death Valley National Park in 2016. Joshua Tree National Park officials warn visitors to do a better job of watching out for wildlife after vehicles ran over and killed at least three desert tortoises.

A handful of picked flowers wilts in the middle of the trail at Diamond Valley Lake on Sunday.

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Visitors enjoy poppies and goldfields along Diamond Valley Lake’s seasonal wildflower trail on Sunday. The trail will be closed until Friday, March 31.

The throngs of people flocking to Southern California’s deserts to see one of the most spectacular wildflower blooms in years now are being asked to show a bit more caution and respect for nature.

Joshua Tree National Park officials this week issued a somber plea for visitors to do a better job watching out for wildlife after vehicles ran over and killed at least three desert tortoises within seven days.

At the same time, officials with the Metropolitan Water District announced they were closing the popular Wildflower Trail above Diamond Valley Lake for two days to install signs asking hikers to stay on the trail.

Too many people were going off the trail to pose for photographs with the California poppies, blue dicks, and other blooming annuals that are unusually abundant this spring because of this winter’s drenching rain storms. Some of the plants got trampled.

The water district expects the trail to be re-opened the morning of Friday, March 31.

The wildflower bloom has been both beneficial and hazardous to the desert tortoise, which has been listed as threatened with extinction.

In the higher altitude Mojave Desert, the combination of warmer temperatures and abundant greenery have brought desert tortoises out of their underground burrows to feast on desert dandelions and other annuals before those leafy plants dry up during the approach of summer.

The tortoises at Joshua Tree National Park are eating so much now that their beaks are stained green, said Michael Vamstad, a wildlife biologist for the park.

“They are eating and foraging like crazy,” Vamstad said. “They’re putting on weight and getting the nutrition they need.”

Meanwhile, thousands of people are visiting the park, many attracted to the colorful flower blooms. The park had 2.4 million visits last year, but is now on track for about 3 million visits this year, Vamstad said.

But the combination of tortoise activity and crowds of visitors became tragic this month when three of the reptiles were killed by cars. The popular park normally gets about one such tortoise death in a year.

Two of the tortoises were killed in the Indian Cove campground area and the other was hit on Pinto Basin Road.

“Three in a period of a week was unprecedented,” Vamstad said. “So we are saying people have to slow down and start looking for wildlife. I think it was an aberration. At least I hope it was an aberration.”

Desert tortoises also are foraging at the Mojave National Preserve, which is bisected by Kelbaker Road and other paved roadways, said Debra Hughson, a park service wildlife biologist.

About five tortoises a year are reported as killed by vehicles there, said Hughson, adding the number of deaths is likely higher because not all are reported.

She cautioned that tortoises sometimes crawl under parked cars for the shade.

“We always tried to educate people to look under your car before you get in, start it and move it,” Hughson said.

The Joshua Tree National Park and Mojave National Preserve are increasingly becoming more important habitat expanses for the desert tortoise.

In the past decade, the reptile has lost habitat in the Mojave Desert because of the expansion of military training area at Fort Irwin and the development of large-scale solar plants in Ivanpah Valley, which straddles the California-Nevada border.

The United States Marine Corps will soon move about 1,500 tortoises out of 137 square miles of the Johnson Valley that was added to the Twentynine Palms training base in 2013. The move will allow the area to be used for live ammunition training missions.

David Danelski is an investigative and environmental reporter for The Press-Enterprise newspaper in Riverside, California. He has been with the newspaper since 1990 and has previously covered crime, transportation and city government. He is married to Lorrie Cobain, a teacher and staff development specialist for the Riverside Unified School District. The couple has one adult daughter, Rosemary. who lives in New York City.